Applicators are known for spot application of pesticides to plants. However, many spot applicators are for the application of liquid pesticides and require complicated valve systems to control the flow of the liquid.
Recently, there has been a desire to move away from liquid pesticides for spot applications and instead to use solid forms of pesticide. Such pesticides are solid at ambient temperatures and allow the application of pesticide directly to the plant, in a controlled amount, while reducing unwanted spillage onto surrounding foliage or soil.
An applicator for solid pesticide composition is taught in U.S. Pat. No. 4,882,874 issued Nov. 28, 1989. The disclosed applicator retains the block of pesticide in a paper sleeve and requires that knurls or indents be formed in the sleeve, or fasteners, such as staples, be inserted through the sleeve to engage the block and maintain the block in the sleeve. In use, this form of attachment requires that the applicator be discarded or reloaded once the block has been reduced to the level of the attachment. Thus, much of the pesticide block is wasted. In addition, the mechanical arrangement whereby the pesticide is advanced along the sleeve of the applicator has been found to fail in some instances. An applicator is required which overcomes these drawbacks.
Solid pesticide compositions are also known. Because of the hydrophobic nature of common solid carrier materials, such as wax, and the hydrophillic nature of many commonly employed pesticides, such as amine herbicide formulations, problems arise in the preparation of the solid pesticide. Since the two phases are naturally immiscible, surfactants are required to allow the production of a solid form without stratification. However, the surfactants, such as fatty amides, may themselves create adverse side effects. In addition, the cost of the solid pesticide is increased by the addition of such surfactants.